Eurasian badgers are highly adaptable and live in a wide variety of environments. Ideal habitat includes deciduous, conifer, or mixed woodlands adjacent to open fields. In addition, they may occupy hedges, scrub, and riverine habitats as well as agricultural land, grassland, steppes, and semi-deserts. When searching for a sett location, they prefer tree-, shrub- and rock-covered areas that will cover the entrance to their sett. Other favorable sett conditions include well-drained soils that that are easy to excavate and are relatively free of human disturbance. They also prefer areas with a moderately wet climate and rich pastures, as these are optimal conditions for earthworms, one of their primary prey. Average elevation for Eurasian badgers is 1000 m. Occasionally, they are found in suburban and urban areas of Great Britain, where human population densities are high. ("Badger", 2002; Balestrieri, et al., 2009; Delahay, et al., 2008; Gehrt, et al., 2010; da Silva, et al., 1993)
Eurasian badgers have a stocky body with short robust limbs and a short tail. Female mass ranges from 6.6 to 13.9 kg, and male mass ranges from 9.1 to 16.7 kg. Males and females do not differ in head-body length, which ranges from 56 cm to 90 cm. Tail length ranges from 11.5 cm to 20.2 cm. Eurasian badgers are known for their distinguishing dark stripes that run from their nose, through the eyes and to each ear. These two dark stripes are separated by a white medial stripe. Dorsal pelage is grizzled gray, and each individual hair is white at the base and darker at the tip. Venter pelage tends to be dark gray or black. Their skulls (dorsal view, ventral view, lateral view) are massive and heavy with a prominent sagittal crest and short, triangular paroccipital processes. Eurasian badgers have flattened molars, small incisors, and prominent canines. The teeth of Eurasian badgers are well suited for an omnivorous diet. The dental formula is I3/3, C1/1, P4/4/, M1/2 = 38. (Lariviere and Jennings, 2009; "Badger", 2002; Delahay, et al., 2008; Kruuk, 1989; Lariviere and Jennings, 2009)
Throughout their geographic range, Eurasian badgers are divided into 24 subspecies, eleven of which can be found in the former Soviet Union. Subspecies generally differ from each other by general color tone and often, general dimensions, skull size, upper molar form, and presence of premolars. However, most of these characteristics are not well-defined. ("Badger", 2002)
Eurasian badgers are usually polygynous. For those living in social groups, only the dominant male and female mate. Males do not defend access to estrous females from other males, but expend much more energy protecting mates from potential predators, such as African lions. Extra-group matings occur frequently. Females may advertise estrous to extra-group males through scent marking. Often, males expand territory ranges during breeding season in an attempt to include more females within their territories, and thus increase their number of matings. (Cresswell, et al., 1992; Delahay, et al., 2008; Revilla and Palomares, 2002; Yamaguchi, et al., 2006)
Eurasian badgers breed year-round; however, most breeding occurs during late winter/early spring (February through May) and during late summer/early autumn (August through October). Gestation last 9 to 12 months, and litters range from 1 to 6 cubs, with an average of 3. Average birth-weight for Eurasian badgers is 75 grams. Cubs emerge from their dens around 8 to 10 weeks after birth. On average, cubs are weaned by 2.5 months, and male and female Eurasian badgers reach sexual maturity by about one year after birth. ("Badger", 2002; Cresswell, et al., 1992; Delahay, et al., 2008; Lariviere and Jennings, 2009; Yamaguchi, et al., 2006)
In areas with low population densities where badgers tend to be solitary, 90 to 95% of adult females successfully produce and implant blastocysts that proceed to full term pregnancy. Only around 40% of females from high population density areas successfully implant blastocysts and proceed to full term pregnancy. Although more than 90% of females in a given social group are capable of reproducing, most do not. Usually, a single dominant female reproduces, and dominant sows are known to kill the cubs of intragroup sows. However, more than one female in the social group may successfully breed depending upon the quality and abundance of available food resources and the number of setts in the group's territory. (Cresswell, et al., 1992; Delahay, et al., 2008; Kruuk, 1989; Yamaguchi, et al., 2006)
Once eggs are fertilized, they may delay implantation into the uterus. This process occurs during the blastocyst stage for Eurasian badgers and is called delayed implantation or embryonic diapause. Implantation of the egg is partially governed by abiotic conditions such as photoperiod and temperature. Delayed implantation in female Eurasian badgers is coupled with superfetation, or the ability to conceive while pregnant. As a result, mixed-paternity litters are not uncommon. This is beneficial to females as it reduces the risk of infanticide by male badgers. (Delahay, et al., 2008; Yamaguchi, et al., 2006)
Female Eurasian badgers nurse cubs as well as provide solid food after weaning. Non-breeding females have been observed grooming and guarding young in the absence of their mother, but generally Eurasian badgers are not cooperative. Parental investment in Eurasian badgers is minimal, and males provide no care to cubs. In social Eurasian badgers, offspring often have a post-independence association with their mother. (Cresswell, et al., 1992; Delahay, et al., 2008; Yamaguchi, et al., 2006)
The oldest known wild Eurasian badger lived to be 14 years old, however few exceed 6 years of age in the wild. In captivity, badgers may live up to 19 years. Mortality rates of cubs within their first year are high, ranging from 50 to 65%. The mortality rate for adults is 30% for males and 24% for females. (Delahay, et al., 2008)
Compared to most other species belonging to Mustelidae, Eurasian badgers are quite gregarious. Social groups may have between 2 and 23 individuals. Average groups consist of 1 to 6 adults and their offspring, and group-size depends on resource quality and abundance. Social behavior in Eurasian badgers may be due to instability in food availability and foraging conditions. In social populations, each group contains a single dominant breeding pair that performs a majority of reproductive efforts. However, when resources are plentiful other individuals tend to reproduce as well. There is no hierarchy after the dominant breeding pair. Although dominant males have the largest individual territories, male territories frequently overlap. Social groups form primarily through the retention of offspring within their natal group. Migration between groups also takes place. The degree of sociality in Eurasian badgers depends great on environmental conditions. Badgers in low-density populations tend to be more solitary while badgers in high-density populations tend to live in groups. Food availability also influences badger sociality. When food availability is low, badgers belonging to clans may revert to more solitary behavior. ("Badger", 2002; Delahay, et al., 2008; Do Linh San, et al., 2007; Kruuk and Parish, 1987; Kruuk, 1989; Lariviere and Jennings, 2009; Revilla and Palomares, 2002; Roper, et al., 2001; Yamaguchi, et al., 2006; da Silva, et al., 1994; da Silva, et al., 1993)
Group living in Eurasian badgers decreases female reproductive success as typically only the dominant female breeds. Dominant females are also known to kill intra-group cubs that are not their own. Various factors drive Eurasian badgers to form groups rather than remain solitary. Food resources that have high renewal rates or have patchy spatial distribution favor group living because resources are plentiful and localized. Lack of unoccupied habitat suitable for setts also makes group living more favorable because retention of offspring within a natal group is less costly than dispersal. Eurasian badgers do not exhibit the high degree sociality known in other social carnivores, (e.g., gray wolves). For example, they exhibit little cooperative behavior in their breeding biology, suggesting that Eurasian badgers represent an early stage in the evolution of carnivore sociality. (Yamaguchi, et al., 2006; da Silva, et al., 1994)
Eurasian badgers construct large, communal burrow systems called setts. Throughout each group territory there are multiple setts. The main sett generally contains many adults and is centrally located in the group's territory. Younger individuals tend to reside in peripheral setts. Badgers often line their setts with dried grass or other plant material, which are primarily used during winter and autumn. Other resting sites include under rocks, in shrubs, in tree hollows, and in man-made structures that may be scattered throughout a group's territory. Non-sett resting sites are used more frequently during spring and summer. Eurasian badgers are nocturnal with peak activity periods occurring during dusk and dawn. (Delahay, et al., 2008; Lariviere and Jennings, 2009; Loureiro, et al., 2007)
Eurasian badger territories may cover as little as 2500 m^2 or may be as large as a few square kilometers. Territory size depends on food quality and abundance as well as the amount of area suitable for excavating setts. When food availability is low, home ranges tend to be larger. Eurasian badgers are territorial and demarcate territorial boundaries at latrine sights with sub-caudal gland secretions. Although territorial, they are fairly tolerant of animals from other groups. ("Badger", 2002; Delahay, et al., 2008; Do Linh San, et al., 2007)
Eurasian badgers communicate in many different ways. They frequently use postures and visual stances to indicate aggressive behavior. Tail flicking and scraping the hind legs are signs of aggression when individuals feel threatened. Raising of the tail and piloerection are signs of sexual excitement. Badgers also communicate with each other through vocalizations, some of which may be difficult to distinguish from others. Growls from both males and females signify aggression and defense when animals feel threatened. Higher pitched wailing noises signify being attacked. Gurgle noises are used either in aggressive attack or sexual pursuit. Cubs exhibit "whickering" or "keckering" while playing or in trouble. Alarm calls for signaling danger to the rest of the group have not been observed. (Delahay, et al., 2008; Kruuk, 1989; Wong, et al., 1999)
Scent-marking is a key form of communication in Eurasian badgers. Communal latrines as well as subcaudal and anal gland secretions are used to mark group territories. In addition, scent from urine may also indicate the estrus condition of females. Allo-marking of conspecifics using secretions from the sub-caudal gland has also been observed. The purpose of allo-marking may be to create a group-specific odor. (Buesching, et al., 2003; Delahay, et al., 2008; Kruuk, 1989)
Earthworms are one Eurasian badgers' primary food sources and many aspects of badger behavior revolve around attaining them. Eurasian badgers eat multiple species of earthworms. When foraging for earthworms, badgers remain in a relatively small space (roughly one hectare). They grab ahold of their prey using their incisors, and if the earthworm breaks into multiple pieces, Eurasian badgers find and eat the remaining pieces. Eurasian badgers are solitary foragers, regardless of social structure. In addition to earthworms, Eurasian badgers also prey on rabbits, voles, shrews, moles, mice, rats and hedgehogs. They also eat a wide variety of large insects, including beetles, leatherjackets, caterpillars, and wasps. They target wasps, in particular, by eating their nests. Wasps are consumed by badgers seasonally and in larger volumes. Eurasian badgers also eat carrion and occasionally eat birds, frogs, fish, newts, lizards, slugs, and snails. Eurasian badgers also feed on more than 30 different kinds of fruit, including pears, plums, raspberries, cherries, strawberries, acorns, beechmast, and blackberries. Some cereals that they consume include maize, oats, wheat, and occasionally barley. Badgers also eat tubers and occasionally fungi. ("Badger", 2002; Balestrieri, et al., 2009; Cleary, et al., 2009; Delahay, et al., 2008; Gehrt, et al., 2010; Kruuk, 1989; Lariviere and Jennings, 2009; Rosalino and Santos-Reis, 2009)
Apart from humans, adult badgers do not have natural predators. However, wolves, lynxes, and bears overlap geographical ranges with Eurasian badgers and may occasionally prey on them, especially younger badgers. Their fossorial and group lifestyles may help them avoid potential predators. Finally, badgers are notoriously aggressive, which likely plays an important role in predation avoidance. (Delahay, et al., 2008; Fedriani, et al., 1999; Kruuk, 1989)
Eurasian badgers primarily prey on invertebrates and may help control certain insect pest populations. Because they include a large amount of fruit in their diet, they may serve as seed dispersers throughout their native range, and one study found that only a small proportion of seeds ingested by badgers were damaged beyond the point of germination. Eurasian badgers are hosts for many parasites, including cestodes, flat worms, round worms, fleas, ticks, and lice. (Delahay, et al., 2008)
Eurasian badgers may control hedgehog and wasp populations locally. In addition, their hair is frequently used in commercially produced brushes and their skin is often used to make rugs. (Delahay, et al., 2008; Lariviere and Jennings, 2009)
Eurasian badgers may damage agricultural crops as well as fruit gardens in populated areas. They are also known to damage buildings, fences, and gardens due to burrowing. They occasionally kill poultry. Eurasian badgers are vectors for tuberculosis and may occasionally transmit the disease to cattle, which is particularly costly to farmers. (Delahay, et al., 2008; Gehrt, et al., 2010; Kruuk, 1989; Lariviere and Jennings, 2009; Moore, et al., 1999)
Annie Wang (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, John Berini (editor), Animal Diversity Web Staff.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
flesh of dead animals.
either directly causes, or indirectly transmits, a disease to a domestic animal
uses smells or other chemicals to communicate
active at dawn and dusk
in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
an animal that mainly eats all kinds of things, including plants and animals
chemicals released into air or water that are detected by and responded to by other animals of the same species
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
having more than one female as a mate at one time
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them